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JQJ 9083 



Bureau of Mines Information Circular/1986 



Subsidence Investigations 
Over Salt-Solution Mines, 
Hutchinson, KS 



By Robert C. Dyni 




UNITED STATES DEPARTMENT OF THE INTERIOR 



V- 



u^ 



Information Circular 9083 



Subsidence Investigations 
Over Salt-Solution Mines, 
Hutchinson, KS 

By Robert C. Dyni 




UNITED STATES DEPARTMENT OF THE INTERIOR 

Donald Paul Hodel, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 

This report is based upon work done under an agreement between the Solution Mining 
Research Institute and the Bureau of Mines. 




Library of Congress Cataloging in Publication Data: 






pO J 



Dyni, Robert C 

Subsidence investigations over salt-solution mines, 


Hutchinson, KS. 


(Bureau of Mines Information circular; 9083) 






Bibliography: p. 19-20. 






Supt. of Docs, no.: I 28.27:9083. 






1. Mine subsidences -Kansas -Hutchinson. 2 Solution 
Salt mines and mining-Kansas-Hutchinson. I. Title. 
(United States. Bureau of Mines); 9083. 


mining-Kansas-Hutchinson. 3. 
II. Series: Information circular 


TN295.U4 [TN319] 622 s 


[551.3] 


86-600096 



CONTENTS 

Page 

Abstract 

Introduction 

Acknowledgments 

Geologic setting 

Sinkhole failure mechanisms 

Subsurface investigations 

Cargill 1974 sinkhole (first investigation) 

Barton 1952 sinkhole (second investigation) 

Carey 1978 sinkholes (third investigation) 

Carey well 56 (fourth investigation) 

Bureau of Mines surface subsidence investigations 

First and second investigations 

Carey 1978 sinkholes (third investigation) 

Background 

Subsidence-monitoring network design and construction 

Monitoring procedures 

Results — vertical movement 

Results — horizontal movement 

Carey well 56 (fourth investigation) 

Background 

Subsidence-monitoring network design and construction 

Monitoring procedures 

Results 

Interpretation of results 

First and second investigations 

Third investigation 

Fourth investigation 

Conclusions 

References 

bibliography * 

Appendix A. — Final vertical control survey of Carey brinefield 

Appendix B. — Final horizontal control survey of Carey brinefield 

ILLUSTRATIONS 

1. Extent and thickness of Hutchinson Salt Member 3 

2. Cavity collapse with surface deformations 4 

3. Location of Cargill and Barton sinkholes 5 

4. Location of boreholes at Cargill sinkhole 5 

5. Cross sections of Cargill sinkhole 6 

6. Location of boreholes at Barton sinkhole 7 

7. Cross section of Barton sinkhole 8 

8. Location of Carey sinkholes 8 

9. Location of boreholes and subsidence monuments at Carey brinefield 10 

10. Cross section of Carey sinkholes 11 

11. Cross sections of Carey well 56 12 

12. Detail of Bureau-designed subsidence monument 13 

13. Subsidence from R-4 to R-15 14 

14. Subsidence from R-16 to R-39 14 

15. Subsidence from R-40 to R-58 14 



1 


2 


2 


3 


3 


5 


5 


7 


8 


9 


12 


12 


12 


12 


12 


13 


14 


15 


16 


16 


16 


16 


16 


17 


17 


17 


18 


19 


19 


20 


21 


22 



11 



ILLUSTRATIONS— Continued 



16. Subsidence from S-l to S-12 , 

17. Subsidence from S-13 to S-21 , 

18. Subsidence from T-l to T-12 , 

19. Subsidence from T-13 to T-20 , 

20. Horizontal movement of R-4 to R-15. 

21. Horizontal movement of S-l to S-12. 



Page 



15 


15 


15 


15 


16 


16 





UNIT 


OF MEASURE 


ABBREVIATIONS 


USED 


IN 


THIS REPORT 




ft 




foot 




yd 3 




cubic ya 


ird 


in 




inch 




yr 




yr 




pet 




percent 













SUBSIDENCE INVESTIGATIONS OVER SALT-SOLUTION MINES, 

HUTCHINSON, KS 



By Robert C. Dyni 1 



ABSTRACT 

The Bureau of Mines in cooperation with the Solution Mining Research 
Institute conducted surface and subsurface investigations over five 
solution-mined salt cavities in the Hutchinson, KS , area. The purpose 
of these investigations was to determine the mechanisms that lead to the 
formation of sinkholes above collapsed solution cavities. Of the five 
salt-solution cavities investigated, four had collapsed and produced 
sinkholes prior to the time of the investigations; the fifth cavity was 
considered stable. Exploratory drilling and coring operations were con- 
ducted at all five sites; surface stability monitoring was conducted at 
three of them. The results of these studies indicate that excessive 
dissolution at the salt-shale contact of each collapsed cavity produced 
large, unsupported roof spans that ultimately exceeded the structural 
integrity of the overburden. The stable cavity was not exposed to ex- 
cessive dissolution at the salt-shale contact; this limited the roof 
span and ensured a stable cavity. The data also show that surface 
settlement in the vicinity of the two surface-monitored sinkholes con- 
tinued for approximately 7 years after the sinkholes formed, indicating 
that the rubble piles of the collapsed cavities were undergoing gradual 
consolidation. 



'Physicist, Denver Research Center, Bureau of Mines, Denver, CO. 



INTRODUCTION 



The Bureau of Mines is actively in- 
volved in making mineral production com- 
patible with the environment. The forma- 
tion of sinkholes due to the structural 
failure of solution-mined cavities in 
salt is a potentially hazardous event 
that can threaten lives and damage 
or destroy structures and property. The 
Bureau, in cooperation with the Solution 
Mining Research Institute (SMRI), con- 
ducted a series of four investigations 
designed to provide an understanding of 
the physical parameters and mechanisms 
involved in sinkhole formation. The re- 
sults of this research will assist in 
establishing a basis for sound salt- 
solution cavity design that will prevent 
cavity collapse and sinkhole formation. 

Extensive research has been performed 
by SMRI and others in an attempt to un- 
derstand the geologic parameters associ- 
ated with sinkhole formation, but little 
work has been done to correlate 
solution-cavity deformations to ground 
surface movements. 2 Therefore, the pri- 
mary methodologies of the four investiga- 
tions conducted by the Bureau and SMRI 
were designed to correlate these two 
parameters. 

The study sites chosen for the four 
investigations were located over salt- 
solution mining operations in the Hut- 
chinson, KS, area. In 1977 the Bureau 
and SMRI conducted the first investiga- 
tion at a sinkhole that had formed on the 
property of Cargill Salt in October 1974. 
This investigation consisted of a drill- 
ing and coring program designed to deter- 
mine the shape of the underlying solution 
cavity, to evaluate the composition 
and condition of the overburden, and to 
determine the mechanisms that led to the 
formation of the sinkhole. The Bureau 



was responsible for contracting the 
drilling and coring operations; SMRI 
contracted for the analyses of the data 
and preparation of the report of the 
investigation. 

In 1978 the second investigation was 
carried out at a sinkhole that had formed 
in June 1952 on the property of the 
Barton Salt Co. , now owned by Cargill 
Salt. As in the previous investigation, 
a Bureau-contracted drilling and coring 
program was conducted, and the data were 
analyzed and a report of the investi- 
gation was prepared under contract to 
SMRI. 

The third investigation was performed 
in 1979 in the vicinity of two sinkholes 
that had formed in 1978 at the Carey Salt 
brinefield. The Bureau again funded a 
drilling and coring program, and an SMRI 
contractor analyzed the data and pre- 
pared a report of the investigation. The 
Bureau also installed and monitored a 
surface survey network designed to detect 
any ground surface movements associated 
with the two cavity failures. 

The fourth investigation was also 
carried out at the Carey brinefield 
in 1981-82. This investigation differed 
from the other three in that it was con- 
ducted at a brine cavity that had not ex- 
perienced any apparent ground movements 
and yet had a mining history similar 
to those of the neighboring cavities that 
had failed. The subsidence-monitoring 
network installed for the previous inves- 
tigation was extended to accommodate mon- 
itoring of the area over the stable 
cavity. Another Bureau-contracted drill- 
ing and coring program was conducted, and 
the data analysis and report preparation 
were again done under contract to SMRI. 



ACKNOWLEDGMENTS 



The personnel at the Cargill Salt 
Co. and the Carey Salt Division of Pro- 
cessed Minerals, Inc., Hutchinson, KS , 

2 The bibliography preceding the appen- 
dixes at the end of this report lists 
relevant previous research on sinkhole 
formation. 



provided valuable assistance in conduct- 
ing this research. In particular, Larry 
Schulte, vice president and director of 
manufacturing, Carey Salt, made signifi- 
cant contributions to the project by pro- 
viding access to company property and 
company mining records. 



GEOLOGIC SETTING 



The Hutchinson Salt Member of the Per- 
mian Wellington Formation underlies a 
large area of central and south-central 
Kansas and north-central Oklahoma. Fig- 
ure 1 depicts the extent and thickness 
of the Hutchinson Salt Member. The zero 
thickness line in figure 1 indicates a 
depositional edge to the west, northwest, 
north, and northeast. The southwest edge 
of the salt undergoes a facies change 
to anhydrite and dolomite, and the east 
edge is erosional. The salt bed in the 
Hutchinson area is approximately 400 ft 
beneath the surface and has a thick- 
ness of about 325 ft. It consists of 
bedded halite with interbeds of shale. 
Overlying the salt is an aquitard com- 
prised of 350 ft of Permian shales and 
siltstones. The surface deposits that 
overlie the aquitard are aquifers 
comprised of unconsolidated sand and 
gravel beds with a combined thickness of 
about 45 ft (6_, pp. 5-10; 7_, p. 12). 3 A 
complete description of the regional 
geology of the Hutchinson area is given 
by Walters (6, pp. 5-26). 




LEGEND 

— 200'— Thickness of salt deposit in ft 
— Facies change 

FIGURE 1.— Extent and thickness of Hutchinson Salt 
Member. 



SINKHOLE FAILURE MECHANISMS 



According to Hendron (4^ pp. 2-13), 
rapid sinkhole development above solu- 
tion-mined cavities in bedded salt for- 
mations as found in the Kansas region 
requires four conditions: 

1 . The presence of a large unsupported 
roof span at the salt-shale contact. 

2. A large-volume cavity beneath the 
unsupported shale roof. 

3. Triggering mechanisms. 

4. In situ conditions that preclude 
arch formation in the shale roof. 

Large, unsupported roof spans in so- 
lution cavities can be created in 
various ways. The solution mining of 
salt through single boreholes with casing 

■^Underlined numbers in parentheses 
refer to items in the list of refer- 
ences preceding the bibliography and 
appendixes . 



set in the shales above the salt and 
tubing extending into the deposit can 
develop cavities that expose the roof 
rock to the deteriorating action of fresh 
water or undersaturated brine. The prac- 
tice of reverse circulation also leads to 
this condition. Once these layers are 
exposed and come in contact with fresh 
water or brine, they disintegrate and 
lose most of their shear strength and 
arching capacity. When roof rock falls 
from the roof of a solution cavity, the 
resulting rubble pile propagates toward 
the top of the cavity, and at the same 
time the roof becomes progressively 
higher. The distance from the top of the 
cavity to the top of the rubble pile de- 
creases during this process because of 
the bulking of the rubble. If the dis- 
tance between the top of the cavity and 
the top of the rubble pile becomes zero 
before the top of the cavity reaches the 



upper shale surface, then the roof will 
start receiving support by the rubble and 
the bulking process will be stopped 
(fig. 24) . A shallow sinkhole may devel- 
op as a result of the downward deflection 
of the shale roof and the consolidation 
of the rubble pile even though the bulk- 
ing process has been halted (fig. 2B). 
If, however, the distance between the top 
of the cavity and the top of the rubble 
pile does not become zero before the 
roof reaches the upper shale layers, then 
a chimney forms and propagates through 
the upper shale layers to the unconsoli- 
dated soils near the surface. This mate- 
rial then flows down into the remaining 
void and can create a deep sinkhole 
(fig. 2C). 

A trigger mechanism that reduces criti- 
cal support from a marginally stable roof 
can consist of a reduction of brine 
pressure inside the cavity, a reduction 
of the buoyancy effect on shale fragments 
suspended from the roof of the cavity, 
or the removal of critical roof support 
by continuing salt dissolution. Hendron 
(4) indicates that these conditions most 



likely are interrelated and act simulta- 
neously to initiate the failure of a cav- 
ity roof. 

If all four conditions for rapid sink- 
hole development are met, a deep sinkhole 
as shown in figure l£ will most likely be 
the result. If, however, only a large 
unsupported roof span at the salt-shale 
contact and triggering mechanisms are 
present, shallow sinkholes as shown in 
figure 2S can possibly form. Shallow 
sinkholes do not develop as rapidly 
as deep sinkholes, and their dimensions 
may increase with time. As mentioned 
earlier, the bulking process in shallow 
sinkholes does not progress up to the 
ground surface, and no chimney is formed 
in the shale layers. If only the first 
condition is met, the unsupported shale 
layers above the cavity will tend to de- 
flect down into the opening, producing 
subsidence on the ground surface. This 
subsidence develops gradually over a 
long period and affects a large surface 
area over the cavity (4, pp. 3-4). Fur- 
ther analysis on sinkhole failure mecha- 
nisms is provided by Hendron (4). 




FIGURE 2.— Cavity collapse with surface deformations. 



SUBSURFACE INVESTIGATIONS 



The purpose of the subsurface investi- 
gations was to provide information on the 
conditions of the four brine cavities. 
By using drilling and coring procedures, 
information on overburden composition and 
conditions and on general solution cavity 
dimensions was obtained for each brine 
cavity. 

CARGILL 1974 SINKHOLE 
(FIRST INVESTIGATION) 

The site of the first cooperative in- 
vestigation performed by SMRI and the 
Bureau was a sinkhole that had formed 



Hutchinson 




LEGEND 
' ■ * * < Railroad 



Scale, ft 



south of the Cargill salt plant in 
October 1974 (fig. 3). At the time of 
the investigation, the sinkhole had an 
approximate surface diameter of 300 ft 
and a maximum depth of about 60 ft. 

The investigation consisted of drill- 
ing four vertical (V-l to V-4) and two 
30° inclined (1-1 and 1-2) exploratory 
borings in the vicinity of the sinkhole 
(fig. 4). The borings were drilled along 
two perpendicular lines that inter- 
sected at the approximate center of 
the sinkhole. Three of the six borings, 
V-l, V-2, and 1-1, were drilled on the 
northeast-southwest line; this line coin- 
cided with the alignment of a series 
of brine wells in the area. The other 
three borings, V-3, V-4, and 1-2, were 
drilled on the northwest-southeast line. 
The vertical boreholes ranged in depth 
from 268 ft in boring V-2 to 525 ft in 




V-4 



LEGEND 
# Exploratory borehole 
— i — i Railroad 



FIGURE 3. — Location of Cargill and Barton sinkholes. 



FIGURE 4.— Location of boreholes at Cargill sinkhole. 



boring V-3. The inclined boreholes 1-1 
and 1-2 were each about 260 ft in depth. 
Complete details on the drilling and cor- 
ing procedures are given by Hendron (1_, 
pp. 1-2). 

Borings V-3 and V-4 each encountered 
the top of the salt deposit at a depth 
of approximately 420 ft. These borings 
found no evidence of any surface sands 
from the sinkhole, or any voids or dis- 
turbances in the strata overlying the 
salt. Borings V-l and V-2, however, both 
found evidence of voids and disturbances 
in the shale at depths of approximately 
240 to 245 ft, and boring V-l also found 
a large void and surface sands from 
the sinkhole at a depth of about 388 ft. 
These findings indicate that an elongated 
cavity had developed in the northeast- 
southwest direction under the sinkhole, 
caused by the solution activity of the 
neighboring brine wells. The evidence 
also suggests that the roof shale over 



the salt had caved upward about 30 ft at 
the location of boring V-l, and that some 
large block movements of the shale had 
extended as much as 180 ft into the shale 
above the elongated cavity (1_, pp. 7-8). 
Walters (6_, p. 45) suggests that the con- 
figuration of the elongated cavity ex- 
ceeded the span capabilities of the 
overlying rock layers. This allowed the 
failure of these layers to breach the 
uppermost shale layer and permit approxi- 
mately 90,000 yd 3 of sand and gravel 
to move down into the opening (2, p. 2). 
The sand that was encountered in the in- 
clined borings 1-1 and 1-2 indicates that 
an approximately 100-ft-diam chimney of 
sand was located below the center of the 
sinkhole. The sinkhole and the chimney 
both were elongated in the northeast- 
southwest direction, indicating that the 
influence of the underlying cavity elon- 
gated along the line of brine wells 
in the area (1, p. 8). Figure 5 shows 



V-l I-l 



Surface soils 




Sinkhole 



• Chimney 



■ V 


-2 

Surface 






■j^^ 




•jfy \ 




j J\ Shale layers 




■^^ f 




fcrjxi 






— — 








A, Northwest - southeast orientation 



B, Southwest - northeast orientation 



FIGURE 5.— Cross sections of Cargill sinkhole. 



cross-sectional representations of the 
sinkhole. Details of the drilling re- 
sults and the conclusions drawn from 
these results are given in a report by 
Hendron (1). An analysis on the causes, 
mechanisms, and time framework, of the 
sinkhole is given by Walters (6_, pp. 32- 
39, 45-46). 

BARTON 1952 SINKHOLE 
(SECOND INVESTIGATION) 

The second investigation took place in 
1978 in the vicinity of a sinkhole that 
formed in June 1952 on the property of 
the Barton Salt Co. , now owned by Cargill 
Salt (fig. 3). The sinkhole had formed 
in the vicinity of an old brine well 
which was believed to have been drilled 
in the late 19th or early 20th century by 
the G & H Salt Co. The sinkhole had a 
surface diameter of about 250 ft and a 
maximum depth of about 30 ft, and was 
backfilled shortly after it formed. The 
sinkhole now lies beneath a parking area 
and a section of the Cargill plant and 
continues to undergo differential settle- 
ments (_3, p.l; 6_, p. 29). 

The investigation consisted of drilling 
six shallow (S-l to S-6) and five deep 
(V-l to V-5) exploratory borings in the 
vicinity of the sinkhole (fig. 6). The 
six shallow borings extended through the 
unconsolidated surface soils to the upper 
shale surface, and the five deep borings 
extended to various depths in the shale. 
The purpose of the shallow borings was to 
determine the limits of the subsidence 
area by defining the depression in the 
upper shale surface, and to determine the 
locations for the deep borings. Details 
on the drilling and coring procedures are 
given by Hendron (3, pp. 3-5). 

The salt deposit was encountered at a 
depth of 497 ft in boring V-l, 435 ft in 
boring V-3, and 423 ft in boring V-5 
(fig. 7). Boring V-l encountered intact, 
but disturbed, shale down to a depth 
of 442 ft; the remaining 55 ft consisted 
of shale and salt roof-fall rubble which 
filled the solution cavity. Boring V-3 
encountered intact, but disturbed, shale 
down to a depth of 425 ft; the remain- 
ing 10 ft consisted of shale and salt 



-f 



V-2 




+ 



LEGEND 
— Approximate subsidence limits 

Exploratory borehole 
50 



Scale, ft 
FIGURE 6.'— Location of boreholes at Barton sinkhole. 

roof rubble. Boring V-5 did not encoun- 
ter any disturbed shale or roof-fall ma- 
terial, and thus was considered to be 
located outside the affected area. Bor- 
ing V-2 terminated at 260 ft and boring 
V-4 terminated at 406 ft, both because of 
difficulties encountered while drilling. 
The results from the shallow borings in- 
dicate that the upper shale surface ex- 
perienced a downward deflection in an 
area centered around boring V-l. The 
maximum deflection of the upper shale 
surface was measured to be approximately 
25 ft at boring V-l, and the entire af- 
fected area had a diameter of approxi- 
mately 240 ft. Based on the results of 
the deep and shallow borings and gamma- 
neutron logs, Hendron suggests that the 
subsidence over the solution cavity was 



V-5 V-2 

Surface 




FIGURE 7.— Cross section of Barton sinkhole. 

due to deterioration, tensile cracking, 
s toping, and downward movement of the 
basically intact shale mass. From the 
results of the deep borings, Hendron in- 
fers that no salt remained in the cavity 
roof at the location of boring V-l and 
that approximately 20 ft of shale had 
s toped from the top of the cavity. The 
deterioration of the roof ultimately led 
to the loss of the ability of the roof to 
span the cavity by arching, causing the 
roof to break and sag and come to rest on 
the rubble pile that filled the cavity 
C3, PP. 26-31). 

CAREY 1978 SINKHOLES 
(THIRD INVESTIGATION) 

The third investigation, jointly per- 
formed by SMRI and the Bureau, took place 
in 1979 at two sinkholes that formed in 






Carey Blvd. 








^sa — z i ■ — 

William St. 




well 50^-J Carey brinefield 

sinkhole 1 

£•;':•;■:} Well 57 
^->^ sinkhole 



300 



600 

_l 



Scale, ft 
FIGURE 8.— Location of Carey sinkholes. 

1978 around two wells at the Carey Salt 
brinefield (fig. 8). The two wells, well 
50 and well 57, were both part of an in- 
terconnected nine-well gallery. The area 
around well 57 began subsiding on May 31, 
1978, and continued to settle through 
June 2. The resulting depression was ap- 
proximately 120 ft in diameter and had 
a depth of about 10 ft. The area around 
well 50 began to subside on June 7, a 
week after the first movements around 
well 57 were observed, and continued 
to subside for several days, leaving a 



depression approximately 260 ft in di- 
ameter and 13 ft in depth (7, p. 8). De- 
tails on production practices for the 
wells operating in the area at the time 
of the sinkhole formations are given by 
Walters (_7_, pp. 6, 13-15). 

The investigation consisted of explor- 
atory drilling and coring around the 
subsidence areas, and installing and 
monitoring a subsidence-monitoring net- 
work on the ground surface. The Bureau 
installed and monitored the network, 
while SMRI was responsible for supervis- 
ing the Bureau-contracted drilling and 
coring operations. Details on the moni- 
toring network are given in the "Bureau 
of Mines Surface Subsidence Investiga- 
tions" section. 

Five vertical borings (V-l to V-5) and 
one inclined boring (1-1) were drilled in 
the vicinity of the two subsidence areas 
(fig. 9). Borings V-l to V-4 were de- 
signed to determine the subsurface condi- 
tions beneath the depression around well 
57; boring V-5 was designed to delineate 
gallery development between the two sub- 
sidence areas; and boring 1-1 was de- 
signed to determine the subsurface condi- 
tions beneath the depression around 
well 50. Boring V-l was advanced to a 
depth of 456 ft, boring V-2 to 495 ft, 
boring V-3 to 455 ft, boring V-4 to 431 
ft, and boring V-5 to 451 ft. The in- 
clined boring 1-1 was advanced to 347 ft 
(5, pp. 7-10). Details on the drilling 
and coring procedures are given by Hen- 
dron (_5_, pp. 7-10). 

The drilling and coring results in- 
dicated Chat a large, unsupported roof 
span existed above the well 57 solution 
cavity (fig. 10). Borings V-l, V-3, and 
V-4 each found evidence of a thin, 
rubble-filled cavity. Boring V-2, lo- 
cated near the center of the depression 
area around well 57, indicated that this 
same cavity had a much larger verti- 
cal extent in this area. The materials 
recovered from borings V-l and V-3 in- 
cluded intact undisturbed shale, sagged 



and disturbed shale, roof-fall rubble, 
and undisturbed salt beneath the rubble. 
Borings V-2 and V-4 recovered sagged and 
disturbed shale, roof-fall rubble, insol- 
ubles and fallen stringers (V-2 only), 
and undisturbed salt beneath the rubble. 
None of the borings drilled near well 57 
found any evidence of salt in contact 
with the shale that had formed the cavity 
roof; thus, it was inferred that no salt 
remained in the roof of the cavity prior 
to its collapse (5_, pp. 31-40). Hendron 
suggests that the formation of the two 
subsidence areas around wells 50 and 57 
was due to the development of large roof 
spans in the solution cavities where the 
shale had been exposed, softened, and 
cracked during well operation. The com- 
bination of these factors induced roof 
collapse as well as excessive sagging of 
the shale above the roof. Complete fail- 
ure of the overlying shale did not occur 
because the rubble that had stoped from 
the roofs of the cavities provided sup- 
port on which the shale came to rest. It 
is possible that a hydraulic connection 
developed between wells 50 and 57, in- 
ducing the collapse of the overlying 
shale (5, pp. 40-42). Details on the an- 
alysis of the drilling and coring re- 
sults are given by Hendron (5, pp. 31- 
42). 

CAREY WELL 56 (FOURTH INVESTIGATION) 

The fourth investigation took place in 
1982 in the vicinity of well 56 located 
at the Carey brinefield. Well 56 is lo- 
cated in the same gallery that contains 
the failed cavities of wells 50 and 57 
(fig. 9). Although the area around well 
56 had not experienced any measurable 
ground surface movements, the stability 
of the solution cavity was unknown. Sur- 
face monitoring would either confirm its 
continued stability or detect any pos- 
sible movements. The exploratory drill- 
ing program would determine whether or 
not the solution cavity was stable, if 



10 



R-4o 



MV-5Q 



S-|o o o o o d.boooooS-12 



MV-4Q 



MV-3Q 



MV-2G 




MV-IO 



T-IO 



100 200 

I I I 

Scale, ft 






\ 



\ 



N- 



i 



\ 



\ 

S-13 \ 

- O OO OOS-21 

I-, / 



R-16 



OMV-6 



OT-20 




000|0®00 00 om-9 
G G V-lof X We "' 56 



OR-58 
ON-I 



LEGEND 

o Subsidence monument 

-f- Exploratory borehole 

^' Subsidence boundary 

a Control point 



FIGURE 9.— Location of boreholes and subsidence monuments at Carey brlnefield. 



11 



Well 57 




FIGURE 10.— Cross section of Carey sinkholes. 



the cavity was in some stage of progres- 
sive failure, or if the cavity was pres- 
ently stable but likely to fail in the 
future. 

The investigation consisted of drill- 
ing and coring five (V-6 to V-10) ex- 
ploratory borings and extending the sub- 
sidence-monitoring network to the area 
around well 56 (fig. 9). The Bureau was 
responsible for extending and monitoring 
the network, and SMR1 was responsible for 
supervising the drilling and coring oper- 
ations funded by the Bureau. Boring V-6 
was advanced to a depth of 565 ft, boring 
V-7 to 436.5 ft, boring V-8 to 515 ft, 
boring V-9 to 502.5 ft, and boring V-10 
to 552.5 ft (J2, pp. 8-9). Details on the 
drilling and coring procedures are given 
by Hendron (2, pp. 8-9). 

The drilling and coring results in- 
dicated the shale overlying the solu- 
tion cavity was intact and undisturbed 
to within several feet of the salt- 
shale contact (fig. 11). Near the roof, 
the shale had softened and undergone 



bed separations. The cavity appeared to 
be elongated in the southeast-northwest 
direction with a roof span of about 
150 ft. In the southwest-northeast di- 
rection,- the roof span was estimated to 
be approximately 50 ft. The restricted 
roof span dimensions near the shale were 
most likely due to the fact that well 56 
had been operated by pumping fresh water 
down the tubing that extended close to 
the bottom of the salt deposit. This re- 
sulted in most of the solutioning occur- 
ring deep in the salt and away from the 
overlying shale. The borings also indi- 
cated that there was only a limited 
amount of shale exposed in the roof of 
the cavity that was subjected to deterio- 
ration by fresh water (2^ pp. 37-39). 
Hendron (2^, p. 39) suggests that the lim- 
ited exposure of the shale to the de- 
teriorating action of fresh water beneath 
the well in combination with the limited 
roof spans over the cavity led to a 
stronger roof support and a stable 
cavity. 



12 



Surface 



V-IOV-8 WeM V-6 

n 56 

























Shale 


layers 


































V-7 Well v-9 

[1 56 p Surface 



Surface soils 



Surface soils 



^«a^T 















Shale layers 






















A, Northwest - southeast orientation 



B, Southwest - northeast orientation 

FIGURE 11.— Cross section of Carey well 56. 



BUREAU OF MINES SURFACE SUBSIDENCE INVESTIGATIONS 



FIRST AND SECOND INVESTIGATIONS 

The investigations carried out at the 
Barton and Cargill sinkholes did not in- 
clude surface monitoring programs, 

CAREY 1978 SINKHOLES 
(THIRD INVESTIGATION) 

Background 

In 1979 the Bureau installed a subsi- 
dence-monitoring network around wells 50 
and 57 in the Carey brinefield. A total 
of 154 survey points were used to monitor 
the horizontal and vertical ground sur- 
face movements in the vicinity of the 



two sinkholes. The network consisted of 
1 existing control point, 4 Bureau-in- 
stalled control points, 103 Bureau-in- 
stalled subsidence monuments, 10 Carey- 
installed subsidence monuments, and 
survey marks set on the 6 exploratory 
borings and on 30 brine wells. 

Subsidence-Monitoring Network Design 
and Construction 

The network (fig. 9) was designed to 
monitor any positional changes of the 
ground surface associated with the two 
sinkholes around wells 50 and 57, as well 
as in other areas of the brinefield. The 
S-line (S-l to S-21) and a portion of the 



13 



R-line (R-4 to R-15) subsidence monuments 
were positioned in the area around the 
well 50 sinkhole. These two monument 
lines intersected at right angles near 
the center of the well 50 sinkhole. The 
T-line (T-l to T-20) and the remainder of 
the R-line (R-16 to R-58) monuments were 
positioned in the area around the well 57 
sinkhole. These two monument lines in- 
tersected at right angles near the center 
of the well 57 sinkhole. The monuments 
R-16 to R-58 were also designed to moni- 
tor the area between the two sinkholes 
and were therefore oriented along the 
axis between the two sinkhole centers. 
The MV-line monuments were distributed 
throughout the area around the sinkholes 
to monitor any ground surface movements 
due to neighboring wells. The remain- 
der of the survey points, including the 
wells, boreholes, and previously in- 
stalled survey movements, were used to 
monitor movements of the ground surface 
over a large area around the two sink- 
holes. Control points P-l, P-2, and P-3 
were placed in areas that were considered 
to be stable and not affected by solution 
mining activities; these control points 
were located in areas outside the area 
shown in figure 9. Control points SC-1 
and SC-2 were located in the brinefield 
for the trilateration surveys and were 
checked for stability prior to each 
survey. 

The k control points and the 103 monu- 
ments installed by the Bureau at the 
Carey brinefield were all of the same de- 
sign and construction (fig. 12). The 
monument consists of a small inner pipe 
fitted with a pointed anchor on the bot- 
tom and a reference-marked cap on the 
top, and a large outer pipe which is used 
to drive the anchor below frost depth. 
The inner pipe extends through a cap on 
top of the outer pipe. The outer pipe is 
free to undergo movements due to frost 
heave or swelling and shrinking soils 
without affecting the inner pipe on which 
measurements are made. The monuments 
proved to be very stable and effectively 
guarded against soil distances throughout 
the entire time of the investigation. 



/ Inner pipe cap with 

(.„ w , survey reference point 



'/2-in-OD inner pipe 



I'/^-in-OD outer pipe 




FIGURE 12.— Detail of Bureau-designed subsidence monu- 
ment. 



The wells, boreholes, and structures that 
were used as subsidence monuments all had 
survey marks that provided consistent 
reference points. 

Monitoring Procedures 

The procedures used to monitor posi- 
tional changes in the network involved 
various survey techniques. Trialteration 
and traverse surveying procedures were 
used for horizontal control, and trigono- 
metric and differential leveling proce- 
dures for vertical control. The horizon- 
tal control surveys, as well as the 
trigonometric level surveys, established 
initial and subsequent coordinates and 
elevations by measuring angles and dis- 
tances from control points SC-1 and SC-2 



14 



to the monuments in the network. 
Although SC-1 and SC-2 were located with- 
in the brinefield boundaries, their sta- 
bility was verified before each survey by 
using trilateration and differential 
leveling procedures from control points 
P-l, P-2, and P-3, which were located on 
stable ground away from the brinefield. 
The Bureau began surveying the network in 
June 1979 and continued through February 
1983. A total of 17 vertical and 12 hor- 
izontal control surveys were performed. 



maximum vertical settlement measured was 
1.58±0.04 ft at R-15. From R-16 to R-39 
(fig. 14) the subsidence was concentrated 
in the vicinity of the two sinkholes, 
with less movement at the midpoint be- 
tween sinkholes. Vertical settlement in 
the area around R-16 was 0.18±0.04 ft; 
settlement in the area around the 
midpoint between sinkholes (R-26) was 
0.09±0.04 ft; and settlement in the area 
around R-39 was 0.24±0.04 ft. Data from 
R-40 to R-58 (fig. 15) showed that the 



Results — Vertical Movement 

The results from the vertical control 
surveys indicated that both sinkholes ex- 
perienced vertical settlements between 
June 1979 and February 1983. Appendix A 
contains data from the final vertical 
control survey of the Carey brinefield; 
these data were used to calculate the 
maximum vertical displacements of the 
subsidence monuments. 

Data from the R-line indicated that 
vertical settlements occurred between 
monuments R-7 and R-50. From R-4 to R-15 
(fig. 13) the settlements increased line- 
arly, starting at monument R-8 and con- 
tinuing toward the well 50 sinkhole. The 



0.0 r 



1.0 - 



1.5 - 



2.0 




_L 



J= 



_L 



R-4 R-5 R-6 R-7 R-8 R-9 R-10 R-ll R-12 R-13 R-14 R-15 
SUBSIDENCE MONUMENT 

FIGURE 13.— Subsidence from R-4 to R-15. 



O 

UJ 
Q 
CO 
00 

CO 



0.0 i 



.5 

R-I6 



± 



i i 



I 



R-20 R-25 R-30 

SUBSIDENCE MONUMENT 
FIGURE 14.— Subsidence from R-16 to R-39. 



■ ■ 



R-35 



R-39 



UJ 

o 

z. 

Ul 

9 

CO 

m 

3 
CO 



0.0 ,- 




I.O 
R-40 



J. 



± 



R-42 



R-44 



R-46 R-48 R-50 R-b^ 

SUBSIDENCE MONUMENT 
FIGURE 15.— Subsidence from R-40 to R-58. 



R-54 



R-56 



R-58 



15 



settlement around the well 57 sinkhole 
began at R-49 and linearly increased 
toward the center of the sinkhole. 
The maximum settlement measured was 
0.49±0.04 ft at R-40. 

The S-line showed vertical settlement 
between S-5 and S-20. The line from S-l 
to S-l 2 began movement at S-6 and con- 
tinued to minearly increase to S-12 (fig. 
16). Maximum subsidence of 1.81±0.04 ft 
was measured at monument S-12. Data from 
S-13 to S-21 (fig. 17) showed that move- 
ment began at S-20 and continued to line- 
arly increase to S-13. The maximum sub- 
sidence at S-13 was 0.20±0.04 ft. 

Data from the T-line indicated that 
vertical settlements occurred between T-8 
and T-19. The line T-l to T-12 
(fig. 18) experienced movements that 
started at approximately T-9 and linearly 
increased to T-12; the maximum subsidence 
at T-12 was 0.23±0.04 ft. The line from 
T-13 to T-19 (fig. 19) showed movement 
that began at approximately T-18 and con- 
tinued to linearly increase to T-13, 
where a movement of 0.34±0.04 ft was 
measured. 




S-l S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-IO S-ll S-12 
•SUBSIDENCE MONUMENT 

FIGURE 16.— Subsidence from S-1 to S-12. 

0.0 r 



UJ 

o 

UJ 
Q 
CO 
00 

CO 



-L 



-L 



J_ 



I 



S-I3 S-I4 S-I5 S-I6 S-I7 S-I8 S-I9 S-20 S-2I 
SUBSIDENCE MONUMENT 
FIGURE 17.— Subsidence from S-13 to S-21. 



Results — Horizontal Movement 

The results from the horizontal surveys 
indicated that minor horizontal move- 
ments occurred in the vicinity of the 
well 50 sinkhole. However, the data from 
the surveys were inconclusive as to 
whether any movement had occurred around 
the well 57 sinkhole. Any possible move- 
ments along the R-line from R-16 to 
R-58, from S-13 to S-21, and the entire 
T-line were of a magnitude less than 
could be detected by the surveys; the 
minimum observable movement was cal- 
culated to be ±0.35 ft. Appendix B con- 
tains data from the final horizontal con- 
trol survey of the Carey brinefield; 
these data were used to calculate the 
maximum horizontal displacements of the 
subsidence monuments. 

The R-line monuments underwent horizon- 
tal displacements oriented along the 
line from approximately R-10 to R-14 
(fig. 20). The movement increased line- 
arly in the direction toward the well 50 
sinkhole. The movement at R-14 was ap- 
proximately l.O±0.35 ft. 



o.o 



.5 



_L 



J_ 



J- 




i/> T-l T-2 T-3 T-4 T-5 T-6 T-7 T-8 T-9 T-10 T-l I T-12 

SUBSIDENCE MONUMENT 

FIGURE 18.— Subsidence from T-1 to T-12. 



UJ 

o 

UJ 

q 

to 

0Q 

z> 

00 T-13 T-14 T-15 T-16 T-17 T-18 T-19 

SUBSIDENCE MONUMENT 

FIGURE 19.— Subsidence from T-13 to T-20. 

The S-line monuments underwent hor- 
izontal movements that started at 
approximately S-5 and continued through 
S-12 (fig. 21). The movement was ori- 
ented along the line and increased 
linearly toward the well 50 sinkhole. 



16 



0.5 r- 




R-4 R-5 R-6 R-7 R-8 R-9 R-10 R-ll R-12 R-13 R-14 

SUBSIDENCE MONUMENT 
FIGURE 20.— Horizontal movement of R-4 to R-15. 



I.O r 



0*- 
0.5 r 




E 0^ 
o 



J I I L 



S-l S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-IO S-ll S-I2 
SUBSIDENCE MONUMENT 

FIGURE 21.— Horizontal movement of S-1 to S-12. 

The maximum horizontal movement at S-12 
was measured to be approximately 1.0±0.35 
ft in the direction toward the sinkhole. 

The results of the surveys taken on the 
T-line and the R-line from R-16 to R-58 
were inconclusive as to whether any hori- 
zontal movement had taken place. If any 
movement did occur, it was of a magnitude 
less than could be ascertained by the re- 
sults of the horizontal surveys. 



CAREY WELL 56 (FOURTH INVESTIGATION) 

Background 

As part of the fourth investigation, 
the Bureau monitored a subsidence net- 
work in the vicinity of well 56 located 
at the Carey brinefield. This network 
was designed to detect any positional 
changes of the ground surface due to cav- 
ity failure around well 56. The network 
consisted of 19 Bureau-installed subsi- 
dence monuments. 

Subsidence-Monitoring Network Design 
and Construction 

The area around well 56 was monitored 
by two perpendicular lines of sub- 
sidence monuments (fig. 9). The M-line 
(M-l to M-9) was oriented in the east- 
west direction, and the N-line (N-l to 
N-10) was oriented in the north-south 
direction. The intersection of these two 
lines occurred at well 56. 

The design of the subsidence monuments 
used in the M-line and N-line was identi- 
cal to that used for the monuments in the 
previous investigation (fig. 12). These 
monuments were installed by Carey person- 
nel using the same techniques as were 
used by the Bureau in the third 
investigation. 

Monitoring Procedures 

As in the third investigation, the 
Bureau used trilateration and traverse 
surveying procedures for horizontal con- 
trol of the subsidence-monitoring net- 
work, and trigonometric and differential 
surveying procedures for vertical con- 
trol. The monitoring program began in 
May 1981 and continued through February 
1983. Seven vertical and five horizontal 
surveys were performed. 

Results 



The data obtained from both the verti- 
cal and horizontal surveys indicated that 



no apparent movement had occurred in 
the area around well 56 during the time 
of the fourth investigation. If any 



17 



movement did occur, it was of a magnitude 
less than could be detected by the 
surveys. 



INTERPRETATION OF RESULTS 



FIRST AND SECOND INVESTIGATIONS 

The analyses of results for the 
first and second investigations were not 
performed by the Bureau and are therefore 
omitted from this report. The analyses 
can be found in publications by Hendron 
(J_, _3-jy and Walters (6^). 

THIRD INVESTIGATION 

The survey data indicate that the sub- 
sidence in the vicinity of the two sink- 
holes continued throughout the period of 
the investigation. The results from the 
exploratory drilling program indicate 
that sagging shale beds were resting on 
the roof-fall rubble pile in the well 57 
solution cavity; owing to the similarity 
and proximity of the two wells it was in- 
ferred that the well 50 cavity roof was 
resting on the roof-fall rubble pile in 
the well 50 cavity. The behavior of the 
subsidence around the two sinkholes was 
therefore most likely a result of the 
gradual settling of the sagging shale 
beds that was caused by the continued 
consolidation of the rubble piles on 
which the shale beds rested. As the 
rubble piles gradually compacted, the 
overlying strata responded with a gradual 
downward deflection into the rubble- 
filled cavities. If the consolidation 
processes ceased, the subsidence would 
also gradually cease; however, the subsi- 
dence was not halted, implying that con- 
solidation was still occurring in the two 
collapsed cavities at the end of the in- 
vestigation. It is logical to assume 
that the consolidation processes occur- 
ring in the rubble piles will, at some 
point in time, be completed, and subsi- 
dence still occurring after the comple- 
tion of the investigation will eventually 
decrease and stop. 

The characteristics of the subsidence 
occurring over the two failed cavities 



indicate that gradual yet significant 
settlement of the ground surface can be 
expected after the initial collapse of a 
solution cavity and the formation of 
a sinkhole. This conclusion is further 
supported by the continued settling of 
other major sinkholes in the region; the 
area around the 1952 Barton sinkhole, for 
example, is still experiencing some minor 
deformations (6). It is also logical to 
assume that a larger volume cavity with 
accompanying sinkhole will experience 
surface deformations of greater magnitude 
than a smaller volume cavity; a larger 
volume cavity will contain a larger 
rubble pile, and thus experience more 
initial collapse and eventual consolida- 
tion. This is evidenced by comparing the 
deformations occurring above the well 50 
cavity and the smaller well 57 cavity. 

The symmetry of the ground surface de- 
formations around the two sinkholes was 
due to the geometries of the underlying 
cavities, since the subsidence areas were 
similar in plan to the probable cavity 
geometries. The subsidence around well 
50 was found to extend approximately 
190 ft on the north and west sides of the 
sinkhole. The area east of the sinkhole 
was affected by a drainage canal that 
runs north-south in the vicinity of well 
50 (fig. 9); the canal and its effects on 
the subsidence around the well 50 sink- 
hole are explained later in this section. 
The well 57 sinkhole, however, did not 
have a similar ground surface deforma- 
tion pattern. The subsidence around the 
well 57 sinkhole was elongated in the 
northeast-southwest direction and had a 
total span of approximately 570 ft. The 
span of subsidence in the southeast 
direction was about the same as the di- 
mensions for the well 50 sinkhole subsi- 
dence pattern. This could have been the 
result of a cavity extending in the 
northeast-southwest direction, elongated 
by hydraulic connections to other brine 



18 



wells in the area. However, the drilling 
data cannot confirm or deny this possi- 
bility owing to the limited number of 
holes that were drilled. Since both well 
cavities were located in virtually iden- 
tical geologic settings and were mined by 
similar methods, it is likely that the 
ground surface deformation patterns were 
the result of a consistent failure pro- 
cess that was dependent on the dimensions 
of the two cavities. 

The results from the survey data also 
indicate that well 50 experienced more 
vertical movement than did well 57. Hen- 
dron (5, p. 31) suggests that stoping of 
the well 50 cavity apparently progressed 
higher into the overlying shale beds than 
did stoping of the well 57 cavity, owing 
to a larger, unsupported roof span in the 
well 50 cavity. This would have created 
a larger volume of rubble in the well 50 
cavity. This larger rubble pile would 
consolidate to a greater degree and cause 
more vertical movement of the overlying 
shale beds that were resting on it. This 
in turn would create a sinkhole of 
greater vertical extent. The subsidence 
around the well 57 sinkhole, however, was 
found to have extended much farther hori- 
zontally than the subsidence around the 
well 50 sinkhole. As proposed earlier, 
this was possibly the result of an elon- 
gated solution cavity. 

Much of the ground surface movement in 
the vicinity of the well 50 sinkhole con- 
sisted of both horizontal and vertical 
components, but it is estimated that vir- 
tually all of the ground surface move- 
ments contained both components. The 
horizontal movements around well 50 were 
always vectored toward the center of the 
sinkhole; it was toward the center where 
maximum vertical displacements were ob- 
served. The horizontal movement in the 
area of the well 50 sinkhole produced 
tensional strains which were vectored to- 
ward the area of maximum vertical move- 
ment. Since the well 57 sinkhole had 
formed under nearly identical conditions 
to those at the well 50 sinkhole, it was 
inferred that there had been horizontal 
components of movement accompanying the 
vertical deformations around well 57, al- 
though these movements would have been 



much smaller in magnitude owing to 
smaller vertical movements. 

The surveys also indicate that the 
ground surface between sinkholes had 
experienced considerable amounts of ver- 
tical deformation (with presumed accom- 
panying horizontal deformation). The two 
solution cavities were known to be 
hydraulically connected (5, p. 4); this 
connection may have elongated the two 
cavities along the area of communication. 
When the two cavities failed, the elonga- 
tions could have deformed the ground sur- 
face above them. This explanation would 
be in agreement with the characteristics 
of the elongated subsidence pattern 
around well 57 (fig. 9). 

The drainage canal that runs north- 
south through the brinefield (fig. 9) 
arrested approximately 90 pet of the 
ground surface deformations caused by the 
well 50 sinkhole. The S-line from S-13 
to S-21 was located entirely on the east 
side of the canal; the first portion of 
the S-line was located on the west side 
of the canal, along with the well 50 
sinkhole. The canal is approximately 25 
ft wide and 15 ft deep. This reduction 
in ground surface movement could be ex- 
plained by the fact that the canal 
severed the communication of the top 
15 ft of the surface soil. This would 
totally halt all tensional strains in the 
top 15 ft of the soil that were brought 
about by the formation of the sinkhole. 
The horizontal and vertical displacements 
that were measured would have been the 
result of the communication of the soil 
underneath the canal. 

FOURTH INVESTIGATION 

The results obtained from the drilling 
and coring programs indicated that there 
was no evidence of bed separations, sag- 
ging, or stoping of the roof shales above 
the well 56 solution cavity. The survey 
results verified these findings by indi- 
cating that virtually no ground surface 
movements had occurred in the monitored 
area. It was, therefore, concluded that 
the solution cavity was , stable and not 
undergoing deformational stresses. Since 
the drilling and coring program found the 



19 



well 56 cavity to have a smaller roof 
span than the well 50 or well 57 
cavities, it is apparent 



that smaller 

CONCLUS 



horizontal cavity dimensions were respon- 
sible for creating stable cavity condi- 
tions for well 56. 



The four investigations performed by 
the Bureau in cooperation with the SMRI 
were designed to determine the character- 
istics and parameters of sinkhole for- 
mation over solution-mined salt cavi- 
ties. The results from the exploratory 
drilling and coring investigations indi- 
cated that the Cargill sinkhole, the Bar- 
ton sinkhole, and the two Carey sinkholes 
all were the result of solution-cavity 
roof failures caused by large, unsup- 
ported roof spans and deteriorating shale 
roof rock. In the case of the Cargill 
sinkhole, the cavity roof rock was com- 
pletely breached, forming a chimney that 
piped approximately 90,000 yd 3 of surface 
soil into its interior. The overlying 
shales of the Barton and the two Carey 
solution cavities did not completely 
fail, resulting in these beds sagging and 
resting on the rubble piles in the solu- 
tion cavities. The solution cavity of 
well 56 in the Carey brinefield appeared 
to be stable in that no sagging or major 
deterioration of the overlying shales had 
occurred. 



The results of the surveying programs 
that monitored the ground surface around 
wells 50, 57, and 56 in the Carey brine- 
field indicated a relationship between 
cavity size and subsidence geometry. It 
was inferred from the drilling and coring 
program that the postfailure subsidence 
was due to the consolidation of the 
rubble piles on which the sagging shale 
beds rested. 

It is evident after evaluating the sur- 
face monitoring and the drilling and 
coring data that the large, unsupported 
roof spans that ultimately failed were 
the result of the well completion and 
mining operation procedures used for each 
collapsed solution cavity. These methods 
allowed salt dissolution near the roofs 
of the cavities, creating the large, un- 
supported spans that eventually failed. 
The methods used for salt dissolution in 
the area have now been changed to prevent 
salt dissolution near the top of solution 
cavities so as to limit the dimensions of 
the cavity roofs. The resulting cavity 
configurations should be more stable. 



REFERENCES 



1. Hendron, A. J., Jr., R. E. Heuer, 
and G. Fernandez-Delgado. Final Report, 
Field Investigations at Cargill Sinkhole, 
Hutchinson, Kansas. Solution Min. Res. 
Inst., Woodstock, 1L, Rep. 78-0005-SMRI, 
Aug. 1978, 9 pp. 

2. Hendron, A. J. , Jr. , and P. A. Len- 
zini. Subsurface Investigation at Well 
No. 56 Carey Salt Brinefield Hutchinson, 
Kansas. Solution Min. Res. Inst., Wood- 
stock, IL, Rep. 83-0001-SMRI, Oct. 1983, 
40 pp. 

3. Hendron, A. J. , Jr. , P. A. Lenzini, 
and G. Fernandez-Delgado. Field Investi- 
gations of North Subsidence Area at Car- 
gill, Kansas (Preliminary Report). Solu- 
tion Min. Res. Inst. , Woodstock, IL, Rep. 
79-0001-SMRI, Jan. 1979, 32 pp. 

4. hendron, A. J. , Jr. , G. Fernan- 
dez, and P. Lenzini. Study of Sinkhole 



Formation Mechanisms in the Area of 
Hutchinson, Kansas. Solution Min. Res. 
Inst., Woodstock, IL, Rep. 79-0002-SMRI , 
Jan. 1979, 17 pp. 

5. . Field Investigations of 

Subsidence Areas at Carey Salt Brine- 
field, Hutchinson, Kansas. Solution Min. 
Res. Inst., Woodstock, IL, Rep. 81-0002- 
SMRI, July 1980, 45 pp. 

6. Walters, R. F. Land Subsidence in 
Central Kansas Associated With Rock Salt 
Dissolution. Solution Min. Res. Inst. , 
Woodstock, IL, Rep. 76-0002-SMRI, June 
1976, 144 pp. 

7. . Surface Subsidence Related 

to Saltwell Operation - Hutchinson, Kan- 
sas, 1978. Solution Min. Res. Inst., 
Woodstock, IL, Rep. 79-0010-SMRI , Oct. 
1979, 32 pp. 



20 



BIBLIOGRAPHY 



Chang, C-Y. , and K. Nair. Analytical 
Methods for Predicting Subsidence Above 
Solution-Mined Cavities. Paper in Pro- 
ceedings, Fourth International Symposium 
on Salt (Houston, TX, Apr. 8-12, 1973). 
Northern OH Geol. Soc. , Inc. Cleveland, 
OH, v. 2, 1973, pp. 101-117. 

Dunrud, C. R. , and B. B. Nevins. Solu- 
tion Mining and Subsidence in Evaporite 
Rocks in the United States. U.S. Geol. 
Surv. Map 1-1298, 1981, 2 sheets. 

Ege, J. R. Surface Subsidence and 
Collapse in Relation to Extraction of 
Salt and Other Soluble Evaporites. U.S. 
Geol. Surv. Open File Rep. 79-1666, 1979, 
37 pp. 

Nair, K. , C. Y. Chang, and A. M. 
Abdullah. Analytical Techniques for Pre- 
dicting Subsidence — Time-Dependent An- 
alysis. Solution Min. Res. Inst. , Wood- 
stock, IL, Rep. 72-0007-SMRI, Oct. 1972, 
33 pp. 

Nair, K. , and C. Y. Chang. Investi- 
gation of the Influence of Certain 



Variables on the Subsidence Above Mined 
Areas. Solution Min. Res. Inst. , Wood- 
stock, IL, Rep. 69-0004-SMRI, Dec. 1969, 
53 pp. 

Nigbor, M. T. State of the Art of So- 
lution Mining for Salt, Potash and Soda 
Ash. BuMines OFR 142-82, 1981, 90 pp. 

Piper, T. B. Surveys For Detection and 
Measurement of Subsidence. Solution Min. 
Res. Inst., Woodstock, IL, Rep. 81-0003- 
SMRI, Jan. 1981, 53 pp. 

Serata, S. Annual Report (Nov. 1973- 
Oct. 1974). Development of Research Pro- 
gram for Detection, Prediction, and Pre- 
vention of Surface Failure Over Solution 
Cavities by Using REM Computer Techni- 
ques. Solution Min. Res. Inst., Wood- 
stock, IL, Rep. 74-0005-SMRI, Nov. 1974, 
47 pp. 

Wong, K. W. A Manual on Ground Surveys 
for the Detection and Measurement of Sub- 
sidence Related to Solution Mining. So- 
lution Min. Res. Inst., Woodstock, IL, 
Rep. 81-0003A-SMRI, 1982, 147 pp. 



APPENDIX A. —FINAL VERTICAL CONTROL SURVEY OF CAREY BRINEFIELD 
(Positive values correspond to downward movement) 



21 



Subsidence 
monument 


Movement , 
ft! 


Subsidence 

monument 


Movement , 
ft' 


Subsidence 
monument 


Movement , 
ft 1 


M- 1 


0.02 

.00 

-.01 

-.04 

-.03 

-.01 

-.01 

.00 

.01 

.04 

.01 

-.01 

.02 

-.01 

NA 

.04 

-.01 

-.02 

-.02 

-.04 

-.02 

-.04 

-.01 

-.01 

-.02 

-.02 

NA 

.03 

NA 

.03 

.05 

.13 

.37 

.52 

.74 

1.03 

1.31 

1.58 

.18 

NA 

NA 


R- 1 9 

R-20 

R-21 

R-22 

R-23 

R-24 

R-25 

R-26 

R-27 


NA 
0.22 
.13 
.11 
NA 
.11 
.09 
.09 
.16 
.10 
.12 
.15 
.12 
.14 
.16 
.18 
.29 
.23 
.23 
.26 
.24 
.49 
.42 
.32 
.30 
.30 
.27 
NA 
NA 
NA 
.07 
.04 
NA 
.02 
.03 
.03 
.02 
.01 
.01 
.01 
-.02 


S-2 


0.02 


M-2 


S-3 

S-4 


.03 


M-3 


.03 


M-4 


S-5 


.04 


M-5 


S-6 


.07 


M-6 


S-7 


NA 


M-7 


S-8 


NA 


M-9 


S-9 

S-10 


.75 

NA 


MV-1 


R-28 

R-29 

R-30 

R-31 

R-32 

R-33 

R-34 

R-35 

R-36 

R-37 

R-38 

R-39 

R-40 

R-41 

R-42 

R-43 

R-44 

R-46 

R-48 

R-50 

R-51 

R-52 

R-53 

R-54 

R-55 

R-56 

R-57 


S- 1 1 


1.44 


MV-3 


S-12 

S-13 


1.81 
.20 


MV-4 


S-14 


NA 


MV-5 


S-15 


.15 


MV-6 


S-17 

S-18 


NA 


MV-7 

N- 1 


.09 
.08 


- 

N-3 

N- 4 


S-20 

S-21 


.04 
.04 
.03 


N- 5 


T- 1 


.04 


N-7 


T-2 

T-3 


.04 
.05 


N-8 


T-4 

T-5 

T-6 


.05 


N-9 

N- 1 


.04 
.05 


R-4 


T-7 


.01 


R-5 


T-8 


.02 


R-b 

R-7 

K-8 


T-10 

T- 1 1 


NA 
.08 

.14 


r-9 


T-12 

T-14 

T-15 

T-16 


.23 


R-10 

R-11 

K-12 

R-13 


.34 
.21 
.15 
.10 


R-14 


T- 1 7 


.05 


8.-15 


T-18 


NA 


R-16 


T- 1 9 


.02 


R-17 


R-58 

S- 1 


T-20 


NA 


R-18 






Not availah 
'Movement is el 


le. 
evation ch< 


inge between initia 


1 and final 


. surveys. 





It. — Survey accuracy is ±0.04 ft. The error limits were determined by statisti- 
cally averaging the standard deviations of stable subsidence monuments for all 
surveys. 



22 



APPENDIX B. — FINAL HORIZONTAL CONTROL SURVEY OF CAREY BRINEFIELD 
(Positive values correspond to increasing easting or northing) 



Subsidence 


AEasting, 


ANorthing, 


Subsidence 


AEasting, 


ANorthing, 


monument 


ft 1 


ft 


monument 


ft' 


ft 


M-l 


-0.17 
-.19 
-.06 
-.14 
-.20 
-.16 
-.06 
-.06 
-.04 


0.04 
.02 
.05 
.04 
.01 
.02 
.10 
.11 
.14 


R-20 


NA 

0.22 

.11 

.23 

NA 

.20 

.14 

.19 

-.11 


NA 


M-2 


-0.20 


M-3 


R-21 


-.09 


M-4 


R-22 


1.61 


M-5 


R-25 

R-27 


NA 


M-6 


.17 


M-7 


.18 


M-8 


.03 




.49 


MV-1 


.09 


.03 


R-28 


.17 


-.02 


MV-2 


.07 
.06 


.03 
.03 


R-29 


NA 
.31 


NA 




.09 


MV-4 


.11 

NA 
NA 


.23 

NA 
NA 


R-33 


.13 

.20 

NA 


-.03 


MV-5 


-.08 




NA 




.01 


.04 


R-34 


.27 


-.08 


N- 1 


-.07 
-.29 
-.16 


.05 
.00 
.03 


R-36 

R-37 


-.02 
.25 
.22 


.87 


N-2 


-.05 


N-3 


-.08 




-.18 


.02 




.29 


-.13 


N-5 


.01 


.08 


R-39 


.05 


-.04 




-.22 


-.01 




-.22 


.09 


N-7 


-.11 


.05 




.06 


.07 


N-8 


-.16 
-.03 


.02 
.12 




.04 
.08 


.14 




.13 


N-10 


-.12 
.26 

NA 


.05 
.02 

NA 


R-45 

R-46 


.14 

NA 

.15 


.16 


R-4 


NA 


R-5 


.11 


R-6 


.26 


.01 




NA 


NA 


R-7 


.22 


-.04 




NA 


NA 


R-8 


.17 


-.18 




.26 


.05 


R-9 


.22 


-.40 


R-50 


.28 


.01 


R-10 


.13 
.17 


-.57 
-.62 


R-51 


NA 
.28 


NA 


R-11 




.06 




.26 


-.82 


R-53 


.28 


.04 




.01 


-1.00 


R-54 


.61 


.26 


R- 1 4 


.13 

NA 


-.97 

NA 


R-55 


.33 
.31 


.08 


R-15 


R-56 


-.02 


R-16 


NA 
NA 


NA 
NA 


R-57 


.20 
.25 


.00 


R-17 




.00 




NA 


NA 




.26 


.04 


See footnotes at 


end of appen 


dix. 







23 



(Positive values correspond to increasing easting or northing) 



Subsidence 

monument 


Atasting, 
ft' 


ANorthing, 
ft 


Subsidence 
monument 


AEasting, 
ft' 


ANorthing, 
ft 


S-2 


0.31 
.26 

NA 
.27 
.36 
.45 

NA 
.85 
.97 

NA 

1.12 

-.04 

-.06 

.01 

NA 
.14 
.17 
.17 
.13 
.13 


0.13 

.09 

NA 

-.02 

.08 

.06 

NA 

.09 

.30 

NA 

-.09 

-.11 

-.46 

-.17 

NA 

-.15 

-.13 

-.07 

-.14 

-.12 


T- 1 


0.34 
.34 
.33 
.21 
.28 
.30 
.23 
.26 

NA 
.31 
.32 
.30 
.04 
.08 
.06 
.04 
-.70 

NA 
.05 

NA 


-0. 15 


S-3 


T-2 


-. 15 


S-4 


T-4 


-.15 


S-5 


-.27 


S-6 


T-5 

T-6 

T-7 


-.09 


S-7 


-.12 


S-8 


-.05 


S-9 


T-ll 


-.07 


S-10 


NA 


S-11 

S-12 


.04 
.00 


S-13 


T-12 


.02 


S-14 

S-15 


T-15 


-.19 

-.06 


S-lb 


.04 


S-17 

S-18 

S-19 


T-18 


.06 

-.14 

NA 


S-20 

S-21 




.04 

NA 



NA Not 
1 Moveme 



available, 
nt is change in horizontal coordinates between initial and final surveys. 



NOTE. — Survey accuracy is ±0.35 ft. The error limits were determined by statisti- 
cally averaging the standard deviations of stable subsidence monuments for all 
surveys. 



438ft 420 



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